[twitter] report API errors as generic StopExtraction exceptions

prevents duplicate logging messages for nonexistent users
(#1759)

gallery_dl/extractor/twitter.py

@@ -749,8 +749,8 @@ class TwitterAPI():
                     )
                 except Exception:
                     msg = data["errors"]
-                if response.status_code < 400:
+                if msg and response.status_code < 400:
-                    self.extractor.log.warning(msg)
+                    raise exception.StopExtraction(msg)
             else:
                 msg = ""